KR20040028662A - Fuel injection device for an internal combustion engine - Google Patents

Abstract

The invention relates to a fuel injector comprising a fuel high pressure pump 10 comprising a pump operating chamber 22 for each cylinder of an engine and a fuel injection valve 12 connected to the fuel high pressure pump. The fuel injection valve 12 includes a first injection valve member 28 and at least one first injection port 32 is controlled through the first injection valve member, and the first injection valve member is pump operating chamber 22. It can be moved in the opening direction 29 by pressure against the closing force created therein. The second injection valve member 128 is guided so as to be displaceable in the first injection valve member 28 formed of a hollow, and the at least one second injection hole 132 is controlled by the second injection valve member, and the second The injection valve member can be moved in the opening direction 29 by a pressure against the closing force present in the pressure chamber 40, the second injection valve member 128 being at least indirectly filled with the control chamber 50. Pressurized by a pressure present therein, the pressure being generated by the fuel supply pump 52 such that the second injection valve member 128 can be held or opened in the closed position in accordance with the operating parameters of the engine. .

Description

FUEL INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE}

Such a fuel injection device is known from EP 0 957 261. The fuel injection device includes a fuel high pressure pump for each cylinder of the engine and a fuel injection valve connected with the fuel high pressure pump. The fuel high pressure pump includes a pump plunger which is operated in up and down motion by the engine and which limits the pump operating chamber connected with the pressure chamber of the fuel injection valve. The fuel injection valve includes an injection valve member, at least one injection port being controlled through the injection valve member, and the injection valve member can be moved in the opening direction by pressure against the closing force present in the pressure chamber. The connection between the relief chamber and the pump operating chamber is controlled by an electrically controlled control valve for control of fuel injection. When the pressure in the pump operating chamber and the pressure chamber of the fuel injection valve reaches the injection start pressure, the injection valve member is moved in the opening direction to open the at least one injection port. The size of the injection cross section controlled by the injection valve member is always the same. However, this does not allow for optimal fuel injection under all operating conditions of the engine.

The present invention relates to a fuel injection device for an engine according to the scope of claim 1.

Embodiments of the present invention are shown in the drawings and described in detail in the following description.

1 is a schematic diagram of a fuel injection device for an engine according to a first embodiment.

FIG. 2 is an enlarged view showing a cross section of the portion indicated by (II) in FIG. 1 in the above fuel injection device.

FIG. 3 is an enlarged view showing a cross section of the portion indicated by (III) in FIG. 1 in the above fuel injection device.

4 is an enlarged view showing a cross section of the portion indicated by (II) in FIG. 1 in the fuel injection device according to the second embodiment.

5 is a graph showing a characteristic curve of fuel injection amount progression with time in the fuel injection device described above.

In this regard, the fuel injection device according to the invention having the features according to claim 1 has an additional injection cross section opened or closed by at least one second injection hole through the second injection valve member in accordance with the operating parameters of the engine. Because of this, the injection cross section offers the advantage that it can be optimized and adapted to the operating conditions of the engine. The control of the injection cross section is carried out simply by the pressure generated in the control chamber by the fuel supply pump in accordance with the operating parameters.

The construction and embodiments of the fuel injection device according to the invention are presented in the dependent claims. The second injection, which is typically performed at high load and / or rotational speed of the engine, but not for the blocking of the second injection valve member, which is typically performed at low load and / or rotational speed of the engine. Increased pressure in the control chamber is required to enable the valve's open movement, because the propulsion required for the fuel feed pump is of less importance. The embodiment according to claim 4 makes it possible for the injection starting pressure of the first injection valve member to be changed by the pressure in the control chamber in accordance with the operating parameters of the engine. In the embodiment according to claim 7, increased pressure in the control room is required for the blocking of the second injection valve member, which is typically carried out at low load and / or rotational speed of the engine, and at high load and / or rotational speed No increased pressure in the interior is required. Thus, overpressure of the fuel high pressure pump and the fuel supply pump is prevented because low pressure is generated by the fuel supply pump.

1 to 4 show a fuel injection device for an engine of a vehicle. The engine is preferably a self-ignition engine. The fuel injector consists of a so-called unit injector system or unit pump system, for each engine cylinder a fuel high pressure pump 10 and a fuel injection valve 12 connected to the fuel high pressure pump. ). In the embodiment of the unit pump system, the fuel high pressure pump 10 is disposed away from the fuel injection valve 12 and connected to the fuel injection valve via a conduit. In the illustrated embodiment, the fuel injection device consists of a unit injector system and the fuel high pressure pump 10 and the fuel injection valve 12 are directly connected to each other to form a component unit. The fuel high pressure pump 10 includes a pump plunger 18 which is hermetically guided in a cylinder bore 16 in the pump body 14, the pump plunger being opposed to the restoring force of the restoring spring 19 of the engine. The cam 20 of the camshaft is operated in vertical motion. The pump plunger 18 limits the pump operating chamber 22 in which fuel is compressed under high pressure during the supply stroke of the pump plunger 18 in the cylinder 16. The pump operating chamber 22 is supplied with fuel from the fuel tank 24 of the vehicle in a manner not described in detail in the intake stroke of the pump plunger 18.

The fuel injection valve 12 includes a valve body 26 which may be composed of a plurality of parts, and within the bore 30, the first injection valve member 28 is guided in a longitudinal direction to be displaceable. . As shown in FIG. 2, the valve body 26 comprises at least one, preferably a plurality of first injection holes 32 in the end region of the valve body towards the combustion chamber of the engine cylinder, which injection valves. It is arrange | positioned over the periphery of the main body 26. The first injection valve member 28 comprises a sealing surface 34, for example in the form of a conical shape in its end region directed to the combustion chamber, which is in the valve body 26 of the valve body facing the combustion chamber. Interacting with the valve seat 36 configured in the end region, a first injection port 32 is guided from or towards the valve seat. An annular chamber 38 is provided in the valve body 26 between the injection valve member 28 and the bore 30 toward the valve seat 36, which annular chamber is opposed to the valve seat 36. In the end region, it passes through the radial extension of the bore 30 and into the pressure chamber 40 surrounding the first injection valve member 28. The first injection valve member 28 is reduced in cross section by The toroidal surface 42 is exposed to the height of the pressure chamber 40. A pretensioned first closing spring 44 engages the end of the first injection valve member 28 opposite the combustion chamber, by which the first injection valve member 28 presses against the valve seat 36. do. The first closing spring 44 is disposed in the first spring chamber 46 of the valve body 26 connected to the bore 30.

The first injection valve member 28 of the fuel injection valve 12 is hollow and has a second injection valve member 128 in a bore configured coaxially within the injection valve member 28 within the fuel injection valve 12. ) Is displaceably guided. At least one second injection hole 132 is controlled in the valve body 26 by the second injection valve member 128. At least one second injection hole 132 is displaced toward the combustion chamber with respect to the at least one first injection hole 32 in the longitudinal axis direction of the injection valve members 28, 128. The second injection valve member 128 comprises a sealing surface 134, for example in the form of a cone, in the end region facing the combustion chamber, which is in the valve body 26 an end region of the valve body facing the combustion chamber. Interacts with a valve seat 136 configured therein, and a second injection port 132 is guided from or towards the valve seat. The second injection valve member 128 may comprise two parts, a first part including the sealing surface 134 and facing the combustion chamber, and a second part away from the combustion chamber and connected to the first part. have. When the sealing surface 142 is formed adjacent to the combustion chamber side end of the second injection valve member 128 adjacent to the second injection valve member, and the first injection valve member is opened in the sealing surface, the pressure chamber 40 The pressure present in) acts.

1 and 3, in the valve body 26, the first spring chamber 46 is connected to the second spring chamber 146 apart from the combustion chamber and the second spring chamber is connected to the second spring chamber 46. A second closing spring 144 is disposed which acts on the injection valve member 128. The diameter of the second spring chamber 146 is slightly smaller than the first spring chamber 46. The first injection valve member 28 protrudes into the first spring chamber 46 by an end and is supported by the first closing spring 44. The first closing spring 44 is supported by a sleeve 47 disposed between the first spring chamber 46 and the second spring chamber 146 by an end opposite the first injection valve member 28. The sleeve 47 is supported at the annular shoulder again formed by diameter reduction at the transition from the first spring chamber 46 to the second spring chamber 146. The sleeve 47 may be press-fitted into the first spring chamber 46 to be fixed or alternatively within the first spring chamber 46 may be displaced in the direction of the longitudinal axis of the first injection valve member 28. . The second injection valve member 128 protrudes into the second spring chamber 146 through the sleeve 47 and is supported by the second closing spring 144 through the spring seat 147. The second closing spring 144 is supported at the bottom of the second spring chamber 146 as an end opposite the second injection valve member 128. On one side the sleeve 47 and on the other side the spring seat 147 restricts the control chamber 50 between the first spring chamber 46 and the second spring chamber 146.

A passage 48 is led from the pump operating chamber 22 through the pump body 14 and the valve body 26 into the pressure chamber 40 of the fuel injection valve 12. The connection of the pump operating chamber 22 and the relief chamber is controlled by an electrically controlled valve 23, wherein the relief chamber is at least indirectly maintained at a slightly increased pressure relative to the fuel tank 24 or the fuel tank. It can be used as an area. While the fuel injection is not performed, the connection between the pump operating chamber 22 and the relief chamber is opened through the control valve 23 controlled by the electronic control apparatus 54 so that high pressure is established in the pump operating chamber 22. Can't be. When fuel injection is performed, the pump operating chamber 22 is separated from the relief chamber by the control valve 23 so that a high pressure can be configured in the pump operating chamber 22 at the supply stroke of the pump plunger 18. Can be. The control valve 23 may be composed of a solenoid valve or a piezo valve.

1 to 3 show a fuel injection device according to the first embodiment. The control chamber 50 is connected to a pressure source, for example in the form of a fuel supply pump 52 which draws in fuel from the fuel tank 24. The delivery pressure generated by the fuel feed pump 52 is controlled in particular by operating parameters of the engine, in some cases other parameters, such as load, rotational speed, temperature. The operation of the fuel supply pump 52, in particular the rotational speed of the fuel supply pump, can be controlled by the control device 54 in accordance with the operating parameters. A pressure limiting valve 56 controlled by the control device 54 and limiting the delivery pressure generated from the fuel supply pump 52 to a predetermined value is provided between the control chamber 50 and the fuel supply pump 52. It can be provided in the connection. In the valve body 26, a passage 58 connected to the control chamber 50 is configured, and the control chamber 50 is connected to the fuel supply pump 52 through the passage. The passage 58 may extend up to the control valve 23, whereby fuel is supplied even if the control valve 23 is opened at the intake stroke of the pump plunger 18 by the fuel supply pump 52. It may be supplied into the pump operating chamber 22 through the passage 58. The pressure surface of the passage 58 and the fuel supply pump 52 also acts as a relief chamber that can be connected with the pump operating chamber 22 by a control valve 23 to control fuel injection. Preferably only the fuel supply pump 52 is provided for the fuel injection device of the entire cylinder of the engine.

The second injection valve member 128 is sealed toward the second valve seat 136 in the valve body 26 by the closing surface 134 through the second closing spring 144. The pressure present in the control chamber 50 creates a force acting on the second injection valve member 128 against the force of the closing spring 144 via the spring seat 147. Since the second closing spring 144 includes a strong pre-tensioning force, if the pressure in the control chamber 50 is low even when the pressure in the pressure chamber 40 of the fuel injection valve 12 is high, the second closing spring The second injection valve member 128 may be fixed to the closed position of the second injection valve member, and when there is an increased pressure in the control chamber 50, the second injection valve member 128 may be opened. When the sleeve 47 is fixed in the first spring chamber 46, the pressure present in the control chamber 50 does not act on the first injection valve member 28. However, when the sleeve 47 is displaceable, as the pressure in the control chamber 50 increases, the sleeve 47 forming the support of the first closing spring 44 is displaced to pre-tension the first closing spring 44. Increases, thereby increasing the injection start pressure of the first injection valve member 28.

The function of the fuel injection device according to the first embodiment is described below. In the intake stroke of the pump plunger 18, the control valve 23 is opened so that fuel is reached from the fuel tank 24 into the pump operating chamber 22. In the supply stroke of the pump plunger 18, the control valve 23 is closed to separate the pump operating chamber 22 from the relief chamber, and a high pressure is configured in the pump operating chamber 22 to determine the fuel injection start. According to the operating parameters of the engine, the pressure generated by the fuel supply pump 52 and present in the control chamber 50 is set. When lower pressure is generated in the control chamber 50 by the fuel supply pump 52, the second injection valve member 128 is closed by the second closing spring 144 having a large force, thereby closing the second injection valve member. The face 134 is closed to the valve seat 136 side. The pressure in the pump operating chamber 22 and thus the pressure in the pressure chamber 40 of the fuel injection valve 12 is high to create on the first injection valve member 28 through the exposed annular surface 42 by this pressure. When the pressure applied is greater than the force of the first closing spring 44, the first injection valve member 28 is lifted from the valve seat 36 by the sealing surface 34, and the at least one first injection hole 32 is The fuel injection valve 12 is opened by opening. The closing force exerted on the second injection valve member 128 by the second closing spring 144 is controlled by the second injection valve member 128 through the pressure surface 142 by the pressure present in the pressure chamber 40. Larger than the force exerted on the phase, the second injection valve member 128 is maintained in the closed position. Thus, in the fuel injection valve 12, only the portion of the entire injection cross section is opened to the first injection hole 32 so that only a small amount of fuel is injected.

When the second injection valve member 128 is opened, an increased pressure is created in the control chamber 50 by the fuel supply pump 52, which is increased by the second injection valve via the spring seat 147. The force acting on the member 128 and supports the force generated on the second injection valve member 128 in the open direction through the pressure surface 142 by the pressure present in the pressure chamber 40. When the pressure in the control chamber 50 generated by the fuel supply pump 52 and the pressure in the pressure chamber 40 generated by the pump plunger 18 are sufficiently high, a second injection is made to the first injection valve member 28. The valve member 128 is further opened, opening the second injection hole 132. This opens all injection cross sections at the fuel injection valve 12, and more fuel is injected. The end of the fuel injection is determined by opening the control valve 23, whereby the pump operating chamber 22 is connected with the relief chamber, in which the high pressure can no longer be configured.

The size of the injection cross section formed by the first injection hole 32 and the second injection hole 132 is at least about the same, so that when only the first injection valve member 28 is opened, half of all injection cross sections can be opened. . Optionally, the first injection hole 32 may form an injection cross section larger or smaller than the second injection hole 132.

5 shows the characteristic curve of the fuel injection amount Q progression over time t during the injection period. Since the pressure in the control chamber 50 is set low at the start of fuel injection, when the supply stroke of the pump plunger 18 is small, only the first injection valve member 28 is opened and the fuel injection valve 12 has an overall injection cross section. Only one part of can be opened. The preliminary injection of the small amount of fuel indicated by the injection step I of FIG. 5 is performed by the first injection port 32. If the supply stroke of the pump plunger 18 is increased, an increased pressure can be set in the control chamber 50, thereby further opening the second injection valve member 128, and at the fuel injection valve 12 altogether. The spray cross section is opened. A large amount of fuel injection is indicated by the first injection hole 32 and the second injection hole 132 indicated by the injection step II in FIG. Optionally, at the start of fuel injection, the pressure in the control chamber 50 can be set such that only the first injection valve member 28 is opened so that at least one first injection port 32 is opened, while fuel injection is performed. The pressure in the control chamber 50 may be set such that the second injection valve member 128 is opened to open at least one second injection hole 132. Thus, as shown in FIG. 5 for injection step II, a small amount of fuel per unit of time is injected through the first inlet 32 at the beginning of the fuel injection and a large amount of time per unit of time during the fuel injection is performed. Stepped fuel injection is performed in which fuel is injected through the first injection hole 32 and the second injection hole 132. The time point at which the second injection holes 132 are opened is determined by the pressure in the control chamber 50. In Fig. 5, the possible effect of the fuel injection amount being increased by the pressure in the control chamber 50 is shown in broken lines. In addition, the second closing spring 144 acting on the second injection valve member 128 irrespective of the pressure in the control chamber 50 is shown as a solid line with respect to the injection step II in FIG. The second injection valve member 128 opens slightly later than the first injection valve member 28. However, the opening timing of the second injection valve member 128 may be changed by the pressure present in the control chamber 50. If only a small amount of fuel is injected at operating parameters of the engine, in particular at low loads and / or rotational speeds, then only the first injection valve member 28 is opened over the entire supply stroke of the pump plunger 18 so that the second The injection valve member 128 may be kept closed.

When the sleeve 47 is displaceable in the first spring chamber 46, the closing force acting on the first injection valve member 28 increases as the pressure in the control chamber 50 increases. As described above, when the pressure in the control chamber 50 rises as the supply stroke of the pump plunger 18 and the load and / or rotational speed of the engine increase, when the first injection valve member 28 is opened, The injection start pressure of the 1st injection valve member 28 which becomes the pressure of the pressure chamber 40 also increases. This also allows the injection start pressure of the first injection valve member 28 to be changed according to the operating parameters of the engine without additional cost.

4 is a sectional view of a fuel injection device according to a second embodiment having the same basic configuration as in the first embodiment. However, in the case of the second embodiment, the control room is arranged in a different position than the first embodiment. The control chamber is defined by a second spring chamber 246 and is limited by a spring seat 147 configured as a plunger in the second injection valve member 128. The sleeve 47 is fixed in the first spring chamber 46 and is not pressurized by the pressure present in the control chamber 246. The pressure present in the control chamber 246 acts on the second injection valve member 128 through the spring seat 147 and supports the force of the second closing spring 144. A passage 58 configured in the valve body 26 in the control chamber 246 is opened, and the passage is connected to the fuel supply pump 52. If there is a low pressure in the control chamber 246, a low closing force acting on the second injection valve member 128 actually created by the pretensioning force of the second closing spring 144. If there is an increased pressure in the control chamber 246, an increased closing force acts on the second injection valve member 128.

The function of the fuel injection device according to the second embodiment is substantially the same as that of the first embodiment. However, its function is that only the first injection valve member 28 remains open, the second injection valve member 128 remains closed at the engine's operating parameters, particularly at low loads and / or rotational speeds, and part of the overall injection cross section. When only the bay is open, the increased pressure is set in the control chamber 246 by the fuel supply pump 52. Correspondingly, when the first injection valve member 28 and the second injection valve member 128 are opened and the entire injection cross section is open at operating parameters of the engine, in particular at high loads and / or rotational speeds, the fuel supply pump ( The low pressure is set in the control chamber 246 by 52).

Claims (10)

A fuel high pressure pump 10 for each cylinder of the engine and a fuel injection valve 12 connected with the fuel high pressure pump, the fuel high pressure pump 10 being operated in up and down motion by the engine, A pump plunger 18 for limiting the pump operating chamber 22 connected to the pressure chamber 40, the fuel injection valve 12 comprising at least one first injection valve member 28, the first injection At least one first injection port 32 is controlled through the valve member, and the first injection valve member can be moved in the opening direction 29 by pressure against the closing force present in the pressure chamber 40, In the fuel injection device for an engine comprising a first electrically controlled control valve 23 for controlling the connection of the pump operating chamber 22 and the relief chamber, The fuel injection valve 12 comprises a second injection valve member 128 which is guided in a displaceable manner inside the first injection valve member 28 constructed as a hollow, and at least one second by the second injection valve member. The injection port 132 is controlled, the second injection valve member can be moved in the opening direction 29 by the pressure against the closing force present in the pressure chamber 40, and the second injection valve member 128 is Pressurized by pressure generated by the pressure source 52, at least indirectly in the fuel-filled control rooms 50, 246 and in accordance with the operating parameters of the engine, thereby opening pressure of at least the second injection valve member 128. The fuel injection device, characterized in that can be changed. 2. A fuel injection device according to claim 1, wherein a common pressure source is provided for all cylinders of the engine. The method of claim 1 or 2, because the second injection valve member (128) is pressurized to react at least indirectly to the closing force by the pressure present in the control chamber (50), thereby increasing the pressure in the control chamber (50). Thereby reducing the closing force acting on the second injection valve member (128). 4. The closing force on the first injection valve member 28 is generated by the first closing spring 44, and the first closing of the first injection valve member 28 or the first injection valve member. Since the support 47 of the spring 44 is at least indirectly pressurized to support the closing spring 44 from the pressure in the control chamber 50, the first injection valve member 28 is caused by the increasing pressure in the control chamber 50. Fuel injection device, characterized in that the closing force acting on the) is increased. 5. The closing force on the second injection valve member 128 is generated by the second closing spring 144, and the second injection valve member 128 causes the plunger 147 to move. Supported by a second closing spring (144), the plunger restricting the control chamber (50) by a cross section of the plunger against the second closing spring (144). The second injection valve member 128 according to any one of claims 3 to 5, because low pressure is generated in the control chamber 50 by the pressure source 52 at a low load and / or rotational speed of the engine. ) Is maintained in the closed position, only the first injection valve member 28 is opened so that the at least one first injection hole 32 is opened, and the control chamber is controlled by the pressure source 52 at the high load and / or rotational speed of the engine. Since high pressure is produced in (50), the second injection valve member (128) is further opened, and the at least one second injection hole (132) is opened. The control chamber 246 of claim 1 or 2, because the second injection valve member 128 is pressurized to support the closing force in the closing direction at least indirectly by the pressure present in the control chamber 246. The closing force acting on the second injection valve member (128) by the increasing pressure is raised. 8. The second injection valve member 128 is maintained in the closed position because the high pressure is generated in the control chamber 246 by the pressure source 52 at low load and / or rotational speed of the engine. Only one injection valve member 28 is opened to open at least one first injection port 32 and low pressure is generated in the control chamber 246 by the pressure source 52 at high load and / or rotational speed of the engine. As such, the second injection valve member (128) is further opened and at least one second injection port (132) is opened. 2. The second injection valve member 132 is maintained in the closed position when the supply stroke of the pump plunger 18 for fuel pre-injection is small by the pressure source 52. The pressure is generated in the control chambers 50 and 246 such that only the first injection valve member 28 is opened to open the at least one first injection hole 32, and the pressure source 52 causes the pump plunger for main injection of fuel ( 18. The fuel characterized in that the pressure is generated in the control chamber 246 such that the second injection valve member 128 is further opened as the supply stroke of 18) is further opened, and the at least one second injection hole 132 is opened. Spraying device. The pressure injection means (52) according to any one of the preceding claims, wherein by the pressure source (52), the second injection valve member (128) is maintained in the closed position when the fuel injection is started, and only the first injection valve member (28) is opened. , Pressure is generated in the control chambers 50, 246 such that the at least one first injection port 32 is opened, and the second injection valve member 128 is further opened in the fuel injection cycle continued by the pressure source 52. And pressure is generated in the control chamber (50, 246) such that at least one second injection hole (132) is opened.